Bump version to v0.8.1.
Bump version to v0.8.1.

cgvarela/htmlbars,duggiefresh/htmlbars,GavinJoyce/htmlbars,mixonic/htmlbars,tildeio/htmlbars,glimmerjs/glimmer-vm,glimmerjs/glimmer-vm,tildeio/glimmer,salzhrani/htmlbars,tildeio/htmlbars,code0100fun/htmlbars,Kuzirashi/htmlbars,chancancode/htmlbars,chadhietala/glimmer,greyhwndz/htmlbars,chadhietala/glimmer,lbdm44/glimmer-vm,jayphelps/htmlbars,mixonic/htmlbars,duggiefresh/htmlbars,greyhwndz/htmlbars,kublaj/htmlbars,lbdm44/glimmer-vm,SerkanSipahi/htmlbars,vinngn1/htmlbars,step2yeung/htmlbars,simudream/htmlbars,tildeio/glimmer,xcskier56/htmlbars,stefanpenner/htmlbars,davidgoli/htmlbars,chancancode/htmlbars,xcskier56/htmlbars,tildeio/glimmer,GavinJoyce/htmlbars,chadhietala/glimmer,Kuzirashi/htmlbars,simudream/htmlbars,glimmerjs/glimmer-vm,chadhietala/glimmer,lbdm44/glimmer-vm,code0100fun/htmlbars,cgvarela/htmlbars,davidgoli/htmlbars,rodrigo-morais/htmlbars,salzhrani/htmlbars,step2yeung/htmlbars,kublaj/htmlbars,rodrigo-morais/htmlbars,stefanpenner/htmlbars,SerkanSipahi/htmlbars,jayphelps/htmlbars,vinngn1/htmlbars